Plans for a Thames Estuary airport have not been shortlisted in an eagerly-awaited aviation report today - but a new Kent airport is still on the cards.

Sir Howard Davies, who heads the government-appointed commission examining airport capacity in the south east, has suggested looking in more detail at expanding Heathrow and Gatwick.

He has not shortlisted any of the estuary airport options as there are "too many challenges surrounding them at this stage" - potentially leaving the door open for the future.

But he is still considering plans for a £50billion airport on the Isle of Grain, promoted by the company of world-renowned architect Lord Foster - famed for designing the Stansted Airport terminal building and London's 'Gherkin' building.

Sir Howard will reach a verdict on the Thames Hub idea - which brings together a new river barrier and crossing, an international airport on the Hoo Peninsula, and a shipping and rail complex - by the end of next year.

And economist Sir Howard said he will deliver a "robust" final recommendation to the government in summer 2015.

There has been widespread opposition to the Mayor of London's scheme - dubbed Boris Island -in Medway as well as Lord Foster's alternative £50billion scheme on Grain.

The decision to not rule out these options completely at this stage leaves uncertainty around the issue for campaigners, Kent MPs and residents.

Former transport minister Paul Clark spoke of the announcement bringing "a grave day for the people of Medway".

The preferred options for meeting the rising demand for air travel in the region come in an interim report by the government-appointed Davies Commission.

The report said: "The commission has not shortlisted any of the Thames Estuary options because there are too many uncertainties and challenges surrounding them at this stage.

"It will undertake further study of the Isle of Grain option in the first half of 2014 and will reach a view later next year on whether that option offers a credible proposal for consideration alongside the other shortlisted options."

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Sir Howard said he will re-examine plans for a hub in the Thames Estuary.

He said: "It's very expensive and it does pose some very significant environmental problems.

"There are important wildlife habitats there and the European directives say that you can only build on them if you haven't got any other alternative and you can provide an alternative habitat."

It announced it will be taking forward for further detailed study proposals for a new runway at Gatwick as well as two proposals for Heathrow.

Kent and Medway reaction to key aviation review

The interim report concluded there is need for one additional runway to be in operation in the south east by 2030, with analysis showing there is likely to be a case for a second extra runway to be operational by 2050.

A detailed analysis of these options will take place before a public consultation in autumn next year.

The Davies Commission recommendation for expansion of Heathrow will prove politically contentious because the Prime Minister has previously said there should not be a new runway there.

Launching the report today, Sir Howard said: "Decisions on airport capacity are important national strategic choices and must be based upon the best evidence available.

"The commission has undertaken a fresh, comprehensive and transparent study of the issues. This report is the product of extensive consultation, independent analysis and careful consideration by the commissioners.

"The UK enjoys excellent connectivity today. The capacity challenge is not yet critical but it will become so if no action is taken soon and our analysis clearly supports the provision of one net additional runway by 2030."

He added: "In the meantime we encourage the government to act on our recommendations to make the best of our existing capacity.

"The commission will now focus on the challenge of appraising the three options, further assessing the case for a new airport in the Thames Estuary, and delivering a robust final recommendation to government in summer 2015."

Launching his vision for a £50bn airport on the Isle of Grain in 2011, Lord Foster said it would be capable of carrying up to 150m passengers a year.

He said that:

• a new nature reserve island could offer new breeding and feeding areas fordisplaced wildlife.
• the wreck of theSS Richard Montgomery, a Second World War ship packed with explosives, poses no danger, as long as it is not disturbed during construction of the airport.
• the risk ofbird strikeson aircraft is not unique to the Thames Estuary and that this risk could be successfullymanaged.
• listed buildingson the Isle of Grain could be included in any new development or dismantled and rebuilt elsewhere.
• investorsare willing to support the planning, design, construction and operation of the airport.

Expansion at Gatwick airport, which has submitted a scheme for a new runway, is supported by Kent County Council.

Gatwick is the world's busiest single-runway airport, but relatively few passengers - about 5% - use Gatwick to transfer to other flights.

It has told the commission there is a "robust and compelling case" for building a second runway to the south of the existing one.

Airport chief executive Stewart Wingate said the expansion would cost between £5bn and £9bn and be financed privately.

A £39bn scheme for a four-runway hub off-shore airport off the east Kent coast was among alternative proposals rejected by the Davies Commission.

The interim report by the commission said the idea by maritime engineers Beckett Rankine for the Goodwin Sands has "fewer benefits than those proposals based on a similar strategic case for an off-shore site in the outer estuary".

The scheme had set out proposals for a round-the-clock airport with high-speed rail link for passengers to connect to London.

The commission also rejected plans by Lydd Airport in east Kent to expand by two runways.

The interim report said there would be "operational and capacity constraints due to its proximity to Dungeness nuclear power station and its associated restricted area of airspace".

It added: "The significant distance of Lydd from London and key centres of demand make this an unattractive prospect."

A proposal by Manston Airport to become a "reliever" airport for the south east region was also dismissed. The report said that while the proposal "presents some potential" it did not address "the large question of London and South East capacity".

North Thanet MP Sir Roger Gale said Manston airport should be used more to relieve pressure on Gatwick and Heathrow.

The Conservative MP said: "It will take years to get runways built at Heathrow or Gatwick and an island airport is pie in the sky for the foreseeable future.

"We therefore have to use the facilities that are available immediately to take some of the peripheral freight and package-tour pressure of Gatwick to in turn relieve Heathrow.

"That means using Manston – an airfield that is, in travelling time, potentially closer to Central London than Heathrow and is available immediately.

"I fear that unless we recognise the immediate concern and bridge the gap the long-term 'solution' may be irrelevant because the fight for this vital business will have been lost."

Kent County Council leader Paul Carter said he favoured the expansion of Heathrow - and that he believed the Isle of Grain scheme would eventually be ruled out.

He said: "In difficult economic times, the question is how you make the best of the existing network - the best option is to expand the runways at Heathrow."

Cllr Carter added: "I think today's announcement kicks it even further into the long grass than it already was.

"If you look at the viability of it and the transport links that are needed - the equivalent of three more high speed rail links to service it - it is just not going to happen."

Lydd Airport executive manager Hani Mutlaq welcomed the interim report.

He said: "We're pleased to see that the commission has recognised the important role that smaller regional airports like Lydd can play in helping to meet the need for greater runway capacity.

"Extra runways at Gatwick and Heathrow may be the favoured long-term solution to easing congestion in the south east, but these options will take many years to complete.

"We need to take immediate action to improve the use of existing runway capacity and ease the pressure on Gatwick and Heathrow."

Today's interim report will be followed by a final one in 2015 - after the election.

For all the breaking news on the Davies report, follow our political editor Paul Francis on Twitter @PaulOnPolitics and reporter Alan McGuinness @Alan_McGuinness.

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